Dopamine-Beta-hydroxylase has been measured in cerebrospinal fluid and plasma from humans and laboratory animals treated with various drugs. Disulfiram treatment of humans caused no significant change in dopamine-Beta-hydroxylase in cerebrospinal fluid or plasma. Administration of disulfiram to monkeys caused no change in cerebrospinal fluid dopamine-Beta-hydroxylase, but induced a large, persistent increase in plasma dopamine-Beta-Hydroxylase. Chronic treatment of cats with monoamine oxidase inhibitors caused a significant decrease in cerebrospinal fluid dopamine-Beta-hydroxylase. The monoamine oxidase inhibitors did not change brain dopamine-Beta-hydroxylase levels. Treatment of cats with phenoxybenzamine or clonidine caused cerebrospinal fluid dopamine-Beta-hydroxylase to change in the predicted directions based on their alpha-antagonist and alpha-agonist properties, respectively.